High quality Yb:Lu3Al5O12 (Yb:LuAG) crystal doped with 10% atom fraction Yb³⁺ was grown by the Czochralski method. After annealing under different atmospheres,the spectral properties of the crystal were characterized. The experiment indicates that the absorption band in 363 nm and 562 nm are connected with Yb2+. After air annealing,the intensity of fluorescence spectra is the strongest and the fluorescent lifetime is the longest. The curve of gain cross-section indicates that Yb:LuAG crystal has a wide emission band. Under laser diode (LD) pumping with 9.59 W power,the maximum output power,the slope efficiency,and the lasing threshold of Yb:LuAG crystal are 3.05 W,41.7%,and 40 mW,respectively.